The father of an infant child risked his own life to save an unconscious driver as his car spun out of control on a busy Sydney highway.

Clayton Thomas said he was minding his own business when he saw an SUV plough into a wall and bounce across four lanes of Monday lunchtime traffic on the M4, in Sydney's west, before it was collected by a truck.

Mr Thomas saw the driver laying unconscious inside the white Mitsubishi Highlander, slumped over the wheel and unable to control the car - which started reversing in circles - so he abandoned his vehicle and jumped into action.

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Clayton Thomas risked his own life to save an unconscious driver as his car spun out of control on a busy Sydney highway

Mr Thomas saw the SUV plough into a wall and bounce across four lanes of lunchtime traffic on the M4 before it was collected by a truck and started reversing in circles

'Mate, I just sort of jumped out and started chasing the car around a bit like Benny Hill style,' he told the Today Show on Tuesday.

Mr Thomas tried to gain access from the outside but realised there was a danger he would be struck by the out-of-control vehicle.